President Donald Trump on Monday hit back at Canadian Prime Minister Mark Carney, who on Friday had announced he would retaliate against any new U.S. tariffs on Canadian goods.

Writing on Truth Social, Trump threatened to hit imported cars, trucks, automobile parts and steel with 50% tariffs starting January 1, 2027.

“Canada has been ripping off the United States of America for years,” Trump wrote. “On Trade, and in other ways, also, they are among the worst Nations in the World to deal with.”

Canada ranks as the third highest source of U.S. imports. In 2025, more than $380 billion worth of goods were brought over the border, according to U.S. Census data.

Monday’s announcement follows a wave of new tariffs that already hit Canada early Saturday morning after weeks-long negotiations between the Washington and Ottawa broke down.

Carney pulled Canadian negotiators out of those talks late Friday after he said the U.S. “proposed new terms that were uneconomic” and “unfair.”

Those 50% duties, which came into effect at 12:01 a.m. ET on Saturday, ensnared a wide swath of Canadian goods, from hockey sticks to building materials.

“We cannot control the storm blowing in from Washington,” Carney said Saturday. “Canada will match Washington’s new tariffs dollar for dollar in order to protect Canadian workers, farmers, families, and businesses.”

Moments before Trump’s social media post, U.S. Trade Representative Jamieson Greer tried to publicly downplay the impact of the tariffs that hit on Saturday morning.

“I think the markets understand that this affects a very small amount of trade,” Greer told CNBC. He added that he would not use the term “trade war” to define Saturday’s tariffs.